Okay kiddo, so a long long time ago in China, some people started following a religion called Buddhism. But not everyone liked it, especially some powerful leaders who believed in a different religion. These leaders wanted everyone to believe in their religion and they didn't like Buddhism getting popular. So, they started persecuting (or being mean to) the Buddhists.
This happened not just once, but four times in China. The first persecution happened in the year 446 when Emperor Tai Wu ordered the destruction of Buddhist temples and statues. The second persecution happened in the year 574-577 when Emperor Wu Zong destroyed many temples, killed many monks and forced the rest to give up their religion. This was a very sad time for the Buddhists.
The third persecution happened in the year 845 when Emperor Wu Zong's grandson, Emperor Wu Zong, ordered the destruction of many temples and killed thousands of monks and nuns. Many people had to hide their religion to avoid being killed.
The fourth persecution was in the year 1300. This time, Emperor Wu Zong's descendant, Emperor Cheng Zong tried to eliminate Buddhism from China. He ordered the destruction of many temples and the execution of thousands of monks and nuns.
But even though the Buddhist people went through a lot of hard times, their religion still survived in China. They just had to practice in secret, until later when it became more popular again. So you see, even when people try to be mean to others because of their beliefs, those beliefs can still survive and even grow.